Thread (103 messages) 103 messages, 16 authors, 2017-12-04

[PATCH v2 06/18] arm64: kvm: use -fno-jump-tables with clang

From: samitolvanen@google.com (Sami Tolvanen)
Date: 2017-11-16 16:25:32
Also in: linux-kbuild, lkml

On Thu, Nov 16, 2017 at 11:46:17AM +0000, Will Deacon wrote:
Can you elaborate a bit more on exactly what you saw failing here,
please?
Mark noticed that clang built kernels fail to boot when the kernel
starts at EL2:

  http://lkml.iu.edu/hypermail/linux/kernel/1711.0/02817.html

Turns out starting with LLVM r308050, the compiler decides to use
a jump table in __init_stage2_translation, and generates code that
branches into an EL1 virtual address.
Whilst it's obviously broken to jump to EL1 from EL2 w/o VHE, the
commit message is a bit cryptic.
I agree, I'll add a more descriptive commit message for v3.

Sami
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